"I'm an entertainer. I'm not saving lives..."

One of our Brit flag-bearers at this year’s Oscar bash, Rachel Weisz talks poverty, pregnancy and doing the red-carpet act

Did you have to audition for the role as Tessa Quayle in The Constant Gardener? Yes and I very much wanted it. The script struck something very deep in my heart. I knew Fernando Meirelles was directing, I’d seen City Of God and I really wanted to work with him. So I took a day off from working in LA, jumped on a plane to London and met him for an hour. Then I turned round, went back to LA and got on with my job. I didn’t hear anything for a couple of weeks so I wrote him a very passionate letter telling him why I felt I should play the role and why I wanted to work with him.

Have you written many letters to directors to seduce them? I’m not quite sure it was seduction! I’ve written to directors after I’ve seen their work, if I see a film I love. Sometimes I write to actors and actresses as well but I hadn’t written a letter before trying to get a job!

What is so different about Meirelles as a director? He works so closely with his cameraman, Cesar Charlone, who was also his cinematographer on City Of God and they tell you to do whatever you want – it’s an extraordinary thing, to value spontaneity and naturalness. So you feel as if you’re in your own house with your husband, you don’t feel as if you’re on a film set. Sometimes technicalities can take over on set and it’s our job to try and stay free within that but they create an atmosphere of complete freedom.

You’ve worked with Ralph Fiennes before… I did a film with him in Hungary, directed by Istvan Szabo, called Sunshine. So this was my second time working with him and I hope I’m given a chance to work with him again – he’s an extraordinary acting partner, inspiring and very committed. I loved working with him.

How did you prepare for the role? Obviously with it being based on John le Carré’s novel, it’s a piece of fiction but it was meticulously researched by John – and I think if you open the newspapers most days there have been debates going on. For HIV for instance, the drugs cost $20 a pill, which is a month’s salary in Africa but there’s this whole issue about patenting rights. That’s something I knew about in advance but beyond that, I really didn’t know very much.

How much of an impact did it have filming the movie in Africa? It was an adventure. Every day there were rewards, meeting these people and feeling their spirit and I’ll always carry that in my heart. The beauty of Africa, where we filmed at Lake Magadi and there were hundreds of bright pink flamingos and when you wake up in the morning the sun’s coming up over the planes of Africa – it’s one of the most beautiful sights in the world. There is a high level of disease, of HIV, and yet the spirit of these people is so strong. We set up a charitable trust and we’re building a school there and we’re going to provide fresh water because it’s a very small amount of money for us but providing an education is a life-changing experience for them.

John le Carré based your character, who’s trying to expose drug-company corruption in Africa, on the late Yvette Pioli. Did you research her? I didn’t really know that much about her. All I knew was that she was a person who would do anything to help protect people that were less fortunate than her. I suppose that was my responsibility playing the role because there are people right now, as we sit here, who are devoting their lives to helping people who are less fortunate than them. These people are putting their lives in danger and my responsibility was to do these people justice. What fascinated me about Yvette was getting inside what drives a person to devote their life to helping other people. I’m in awe.

Was it a relief to play a character where you didn’t have to spend hours in make-up, apart from being made to look pregnant? The make-up artist stuck my prosthetic stomach on with glue and then had to paint it to match my flesh and that is so hard to get it right. It was quite heavy, particularly when it filled with water in the bath! Playing an activist in Africa though, you don’t wear any make-up because it would be ridiculous as an activist to do so.

On to more frivolous matters – is it hell working out what to wear to the Oscars? It’s not real life, is it? I’m a jeans and T-shirt kind of girl. In fact going to a red carpet event is also a role for me, it’s not real life. I don’t have hair and make-up people living in my flat. It’s fantasy, it’s a fairytale and it’s fun wearing a borrowed dress and a beautiful pair of earrings but it’s not reality.